Heat retaining float for glass tank feeding shelves



Dec. 11, 1934. F. G. SCHWALBE HEAT RETAINING FLOAT FOR GLASS TANKFEEDING SHELVES Filed Sept. 12, 1955 2 Sheets-Sheet 2 T1115 m 222 3 fAcfiamfle dbbozmq Patented Dee. Ill, i934 hurrah mar ammo mom son amassram rename smavns Franz G. Schwalbe, Toledo, @hio Application September112, 1933, Serial No. 689,112

4 Claims.

My invention has for its object for maintaining the glass of glass tankdelivery shelves at a uniform high temperature to produce uniform highquality shaped glass. The invention is particu- 5 larly advantageouswhenused in connection with gathering means, such as well knownautomatic blowing or shaping machines, and wherein the shelves are sodesigned as to enable the location of one or more machines in workingjuxtaposition with glass tanks to withdraw molten glass from the tank.In connection with such tanks ordinarily, the shelves are necessarilyshallow and protrude considerably from the tank body to enable dippingand gathering of glass by the molds or other glass gathering device. Theglass is usually drawn into the molds or gathering containers bysuction. By reason of the necessary shallowness or lack of depth of theglass within the shelves, and by reason of the projection of the shelvesfrom the tank body, the heat of the glass radiates readily therefromcausing cooling of the glass and, furthermore, the exposure of thesurface of the glass within the shelf to outside atmosphere, in the formof constructions heretofore used, causes, in like manner, radiation ofheat and chilling of the glass. This causes the gathering of glasshaving different consistency or viscosity into the molds or gatheringcontainers which produces a variation in character of the glass locatedin difierent parts of the articles formed therefrom and consequently theproduction of unsightly glass having irregular contraction that producesdistortion.

By my invention I provide a refractory heat insulating floatable memberof a character similar to that of a wall of the tank itself and locatedon the surface of the glass in the shelf and so as to completely coverthe glass in the shelf except for an arcuate shaped opening described bythe gathering molds of the automatic forming machines, the openingsbeing so formed as to enable the glass gathering molds to dip below thesurface of the glass gathering the glass as they swing along the shelf.The refractory member is so formed as to float on the surface of theglass and consequently completely closes the shelf except that portionformed by the arcuate opening into which the glass gathering mold dips.The edges of the float substantially fit the shelf edge and consequentlyit substantially seals the interior of the shelf as against theradiation of any heat from the glass body and prevents or greatlyreduces cooling of the'glass within the shelf at the surface that wouldotherwise produce lack of uniformity in the character of the articlesproduced from the glass drawn from the shelf. Owing to the fact that thegathering molds or other containers ordinarily gather both the coolerand the hotter glass, there is produced in the finally formed glassarticle glass having irregular refractive characteristics as well asirregular strains that often render parts of the article fragile, whileby my invention the glass gathered has substantially uniform temperaturewhich maintains uniform viscosity and consequently produces a far moreperfect glass article.

The heat insulating block being floated in the glass on the shelfoperates to maintain a uniform working condition of the glassnotwithstanding the change of the level of the glass in the tank as itis used up in forming the articles. The float formsa guide for thesetting of the machine to produce uniform depth of dipping below theglass surface. It also operates in conjunction with the moving gatheringmolds or containers to circulate the glass through the opening in thefloatable heat insulator with great effectiveness by reason of thenarrow width of the opening which is substantially that of the gatheringmold itself, the gathering mold operating to push the glass along theopening, the glass within the opening being at all times confined byreason of the fact that the block floats and maintains its positionbelow and above the glass surface. Hence, upon the entrance or movementof each mold into and along the opening there is produced a completeremoval of the surface glass.

The invention also provides means for maintaining the cut-off glass in apart of the shelf other than that into which the molds are dipped. Thecut-ofl glass gathers in this part and of course settles into the glassand eventually is heated by the glass of the furnace until it has theconsistency of the body of the glass of the shelf.

The invention has for its object to produce glass shelf heat insulatorsof difi'erent forms and to illustrate a practical application of theinvention. I have selected an insulator and two forms of shelfstructures that contain the invention as an example of such structuresand shall describe these particular structures hereinafter. Thefloatable insulator member having the glass delivering port and theglass delivering shelves with which it may be associated, is shown inthe accompanying drawings.

Fig. 1 is a view of a section of a part of the furnace, the shelf, andthe floatable block. Fig. 2 illustrates a top view of the shelf shown inFig. 1. Fig. 3 is a broken view of a section taken on the plane of theline 33, and also illustrates diagrammatically the progressive positionsof the gathering mold as it moves over and dips into the glass of theglass shelf. Fig. 4 illustrates the heat insulating block located withinthe shelf and having a structure that slightly differs from thestructure of the shelf shown in Figs. 1 and 2, and illustrates a meansfor preventing heat radiation from the glass along the outer edges ofthe heat insulating float. Fig. 5 illustrates a broken view of a sectiontaken on the plane of the line 5-5 indicated in Fig. 4.

As shown in the drawings, the tank 1 is provided with the usual bridgewall 2 underneath which the glass 3 flows through the port 5, in themanner well known in the art. openings in the side wall '7, such asindicated at 6, and the delivering shelf 8 protrudes from the lower edgeof each opening 6 to form an extension of the interior of the tank inthe form of a bay for disposing portions of the glass in position suchthat it may be gathered by .the automatic glass forming machines. Theupper edge of the opening 6 is located slightly above the normal glasslevel and the upper edge of the shelf or bay extends to a point slightlyabove the glass level and, hence, the glass flows into the shell and islocated in position so as to deliver the glass to the glass gatheringcontainers or molds of a rotary machine that progressively dip as theypass over each projecting shelf. A plurality of the glass molds 12 areconnected to suitable arms of the glass forming machine, in the mannerwell known in the art. The arms swing over the top of the shelf, themachines being provided with means for causing the descent of the armsand the glass molds as they successively pass over the shelves.

Owing to the fact that a large volume of the glass must be accumulatedin the shelf in order to provide for a suflicient mass of glass forretention of heat, the glass shelves must be so formed as to produce aconsiderable volume of glass within the shelf. The glass ordinarily intime loses heat by radiation from its surface and the surfaces of thewalls of the bay which produces glass of different viscosities in theshelf which results in the production of glass articles having differentcharacteristics in different parts of each article, that is, seeds andgrain appear in the glass articles which causes an objectionalappearance of the glass and produces strains that causes ready fractureof the glass.

In order to reduce the radiation of the heat from the glass in theshelf, I have provided a floatable member having a glass delivering portthat completely covers the glass within the shelf. The float rides onthe surface of the glass and thus seals the inner surfaces of the sidesof the shelf and prevents direct radiation from the surface of the glassexcept from that portion into which the molds 12 dip. Preferably, theinner edge of the float protrudes within the outer surfaceof the Wall 7and within the opening 6 and so as to quite completely seal the glass ofthe furnace within the furnace and the shelf from direct radiationexcept through the port.

As shown in the drawings, the fioatable member 15 has dimensionssubstantially corresponding to the interior horizontal area of the glassdelivering shelf and is formed to have a shape that conforms to theshape of the interior of the shelf at its upper edge. The float 15 isformed of a refractory clay and is rendered floatabl'e, preferably byforming the trough 16 having a suificient depth and width to produce therequired lightness proportionate to thedisplacement of the The tank 1has one or more glass by the member. The trough 16 may be filled with asuitable diatomacious earth or other heat insulating refractory materialof light weight in order to produce floatability and maintain thedesired heat insulation. Preferably, the outer edges of the fioatableinsulator is rounded, as indicated at 1'7, in order to producesubstantially a narrow line of contact with the inner edges of the shelf8. The glass at the line of substantial contact readily chills-and sealswith a highly viscous relatively cold though molten glass the outer edgeportion of the member 15 to the edge of the shelf. This reduces heatradiation and allows for the slight variation of the glass level.

The central portion of the member 15 is provided with an arcuate shapedopening 19 having its center substantially at the center of rotation ofthe arms and the gathering molds 12. Also, preferably, the sides of theopening 19 are inclined, as at 18. -As they extend towards the undersideof the member 15, they are inclined away from the imaginary, arcuate,vertically displaced surface that extends lengthwise of the slot. Thisprovides an inverted funnel shaped part for allowing the glass to movefrom all parts of the shelf towards the upper edge ofthe port 19 and tothe gathering molds 12 as they enter and pass along the port.

, As shown in Fig. '2, the molds enter one end of the port or opening 19and move along the opening and rise near the opposite end of the portand as they rise the glass that adheres is sheared, in

the manner well known in the art, the sheared glass falling into theshelf near the end of the port. The fioatabie member 15 is formed toretain the glass gobs or sheared portions of the glass at the deliveryend of the opening 19. The cutoff portions are, however, soon raised intemperature to the glass of the 'shelf and the glass of the partssheared from the gathering container soon redistributes itself in theglass of the shelf. Preferably, the member 15 is provided with a bridge22 having a wedge shaped outer edge 23 so located as to dispose the edge23 of the wedge portion of the bridge 22 close to and below the level ofthe glass. This forms a drag to the glass that is drawn from the glassin the shelf by the container and when the glass is sheared from thegathering containers 12, it drops into the glass in the shelf throughthe port located on the following side of the bridge 22 where it isretained until the heat of the glass within the shelf raises it to atemperature equal to that of the glass in the shelf and thus gives itthe same characteristic as to viscosity as that of the glass found inthe shelf.

Suitable burners 25 may be provided for heating the glass within thatportion of the furnace in the vicinity of the shelf in the manner wellknown in the art. They operate to maintain the glass of the shelf at ahigh temperature and supply heat lost by radiation and consequently theyaid indirectly in the addition of the necessary heat required to restorethe temperature of portions of the sheared glass to that of the body ofglass of the furnace and the shelf. As illustrated in Fig. 3 thegathering mold 12, shown in what might be termed phantom lines, movesprogressively over the shelf and dips into the glass reaching itsmaximum depth of movement at substantially the point indicated at 12. Itthen rises, dragging with it the gob of glass 26 which drags over theedge 23 of the bridge 22 located slightly below the surface of the glassand carries it into the port 27 or that portion of the arcuate opening19 located on the following side of the bridge 22. The shearing knife 28commonly used for removing the glass that strings from the containerbegins to shear the gob of glass on the following side of the ridge 22,the shear being made complete and so as to drop the gob of glass in theport 27, that is in the part of the opening 19 on the following side ofthe bridge 22. sheared glass and this glass, though slightly cooled bycontact with the atmosphere when raised is reheated by the heat of thebody of the glass of the shelf and consequently soon acquires the sameviscosity of the glass of the shelf.

As succeeding molds sweep through the oblong opening 19, that has awidth substantially the same as that of the gathering mold, acirculatory movement of the glass within the area of the opening andparticularly that portion of the glass at the surface of the shelf andwithin the opening is carried forward and toward the port 27. The molditself operates to remove some of the heat of the glass within theopening 19 and glass cooled by contact with the mold as well as thesurface glass is likewise carried forward towards the delivery end ofthe opening 19. Consequently the structure is such as to produce aconstant movement of hot glass into the opening 19 where it is gatheredby the gathering molds and with much greater efliciency than could beproduced in wide open area of the shelf if the floatable heat insulatorwas not present.

In the form of construction illustrated in Figs. 4 and 5, the shelf edgeis provided with refractory plates 30 and 31 that are supported on theouter side and edges of the walls of the shelf or bay, and overhanging ashort distance the surface of the glass in the shelf so as to makecontact, preferably, with the side surfaces of the floatable member 15.This operates to heat seal that portion of the glass locatedintermediate the side and end walls of the shelf or bay and the Eachsucceeding gathering mold drops the the shelf and floatable on thesurface of the glass in the shelf and having an arcuate glass deliveringport, a suction gathering mold, and means for moving the mold circularlyalong and into the port.

2. In combination with a glass shelf, a refractory member substantiallyfitting the interior of the shelf and floatable on the surface of theglass in-the shelf and having an arcuate glass delivering port, asuctiongathering mold having a glass shearing means, and means for moving themold circularly along and into the port, a bridge part extending acrossthe port near the glass delivering end of the port and forming anauxiliary port for receiving sheared glass.

3. In combination with a glass shelf, a refractory member substantiallyfitting the interior of the shelf and floatable on the surface of theglass in the shelf and having an arcuate glass delivering port, asuction gathering mold having means for moving the mold circularly alongand into the .port, the lateral surfaces of the port inclined outwardlyfrom the upper edge'of the port to enable a free flow of heated glassfrom the shelf into the port and heat radiation from the glass body inthe shelf to the glass within the port.

4. In combination with a glass shelf,-a refractory member substantiallyfitting the interior of the shelf and floatable on the surface of theglass in the shelf and having an arcuate glass delivering port, asuction gathering mold having a glass shearing means and means formoving the mold circularly along and into the port, a bridge partextending across the port near the glass delivering end of the port andforming a main glass glass from the auxiliary port into the shelf andready transmission of heat to the glass within the ports.

FRANZ G. SCHWALBE.

